Electromagnetic interference affects the performance of electrical circuits. Reduction of sensitivity to EMI, as well as the reduction of radiated levels of EMI, is an important consideration in the design of electrical circuits and devices. With increasing power levels and frequency, radiated emissions also rises. Conversely, circuits operating with reduced power levels are particularly sensitive to undesirable radiation.
Designers often rely on gaskets and other shielding measures to reduce EMI radiated emissions. An area of particular interest concerns EMI emission suppression for high density interconnects. Density refers to the number of electrical connections in a given area of a connector. A typical high density connector has 100 pins in the space having dimensions of approximately 38 mm by 10 mm, or an area of 3.8 cm2. An example of an application calling for such a connector is the High Performance Parallel Interface-6400 (HIPPI-6400) protocol. HIPPI-6400 relates to high frequency, digital data transmissions at 6400 Mbit/s of data per direction.
Two types of emissions are common to electronic systems: common mode (CM) and differential mode (DM). Common mode emissions are referenced to earth ground and can be caused by current on the outer surface of a shielded component. This current can be caused by capacitive coupling between the internal current carrying components (signal connector pins, traces or wires) and the shielding components (cable shield or backshells). Because of poor bonding between the different parts of the shielding system or inadequate thickness of the shielding, this current may find its way to the outer surface of the shield and can cause radiated emissions. This radiation can result in failure of a system or component to meet applicable EMI compliance standards.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a connector assembly to address the problem of undesirable EMI emissions without adversely effecting the electrical connection.